This disclosure generally relates to location and roaming approaches in GSM, CDMA, and UMTS networks. Further, this disclosure relates to user plane location approaches in core networks and complementary access networks.
Mobile communications infrastructure is typically conceptualized in two generally separate components: the core network (“CN”) and the radio access network (“RAN”). Together, this infrastructure enables user equipment (“UE”), the RAN, and CN to be developed and implemented separately according to the permissive standards set by organizations such as 3GPP and ITEU. Thus, various types of RANs, such as GERAN or UTRAN, may be paired with a single UMTS CN. Also, the UMTS standards provide for protocol separation between data related to user communications and data related to control of the network's various components. For example, within a UMTS mobile communications network, User Plane (“UP”) bearers are responsible for the transfer of user data, including but not limited to voice or application data. Control Plane (“CoP”) bearers handle control signaling and overall resource management.
As mobile networks transition towards 3G and beyond, location services (LCS, applications of which are sometimes referred to as Location Based Services, or LBS) have emerged as a vital service component enabled or provided by wireless communications networks. In addition to providing services conforming to government regulations such as wireless E911, LCS solutions also provide enhanced usability for mobile subscribers and revenue opportunities for network operators and service providers alike.
Position includes geographic coordinates, relative position, and derivatives such as velocity and acceleration. Although the term “position” is sometimes used to denote geographical position of an end-user while “location” is used to refer to the location within the network structure, these terms may often be used interchangeably without causing confusion, Common position measurement types used in mobile positioning or LCS include, but are not limited to, range, proximity, signal strength (such as path loss models or signal strength maps), round trip time, time of arrival, and angle of arrival. Multiple measurements may be combined, sometimes depending on which measurement types are available, to measure position. These combination approaches include, but are not limited to, radial (for example, employing multiple range measurements to solve for best agreement among circular loci), angle (for example, combining range and bearing using signal strength or round trip time), hyperbolic (for example, using multiple time-of-arrival), and real time differencing (for example, determining actual clock offsets between base stations).
Generally, LCS methods are accomplished through CoP or UP methods. CoP Location (“CoPL”) refers to using control signaling within the network to provide location information of the subscriber or UE. UP Location (“UPL”), such as Secure User Plane Location (“SUPL”) uses user data to provide location information. CoPL location approaches include, but are not limited to, Angle-of-Arrival (“AoA”), Observed Time-Difference-of-Arrival (“OTDOA”), Observed-Time-Difference (“OTD”), Enhanced-OTD (“E-OTD”), Assisted Global Positioning System (“A-GPS”), and Assisted Galileo Navigation Satellite System (“A-GNSS”). UPL approaches include, but are not limited to, A-GPS, and A-GNSS, where this position data is communicated over Internet Protocol (“IP”).
There are two established architectures associated with location determination in modern cellular networks. The architectures are Control Plane (“CoP”) and User Plane (“UP”) architectures. Typically location requests are sent to a network through a query gateway function 1. Depending on the network implementation CoP 15 or UP 10 may be used but not a combination of both, as shown in FIG. 1. Note that queries may also come directly from the target device itself rather than via a gateway. Similarly, CoP or UP may be used but not both.
The difference between user plane and control plane, strictly, is that the former uses the communication bearer established with the device in order to communicate measurements. The latter uses the native signaling channels supported by the controlling network elements of the core and access to communicate measurements. As such, CoPL supports A-GPS—it uses control plane signaling interfaces to communicate GPS data to/from the handset. Similarly UPL may conduct E-OTD—the handset takes the timing measurements but it communicates them to the location platform using the data bearer.
UPL has the advantage of not depending on specific access technology to communicate measurement information. CoPL has the advantage that it may access and communicate measurements which may not be available to the device. Current models require network operators to deploy one or the other, CoPL or UPL.
CoPL uses the native signaling plane of the network to establish sessions and communicate messages associated with location requests and to communicate measurements used for determining location. The control plane is the signaling infrastructure used for procedures such as call control, hand-off, registration, and authentication in a mobile network; CoPL uses this same infrastructure for the performing location procedures. CoPL may utilize measurements made by both the control plane network elements as well as the end-user device being located.
Developed as an alternative to CoPL, Secure User Plane Location (“SUPL”) is set of standards managed by the Open Mobile Alliance (“OMA”) to transfer assistance data and positioning data over IP to aid network and terminal-based positioning technologies in ascertaining the position of a SUPL Enabled Terminal (“SET”).
User Plane Location (“UPL”) does not explicitly utilize the control plane infrastructure. Instead UPL assumes that a data bearer plane is available between the location platform and the end-user device. That is, a control plane infrastructure may have been involved in establishing the data bearer so that communication may occur with the device but no location-specific procedural signaling occurs over the control plane. As such, UPL is limited to obtaining measurements directly from the end-user device itself.
SUPL includes a Location User Plan (“Lup”) reference point, the interface between the SUPL Location Platform (“SLP”) and SET, as well as security, authentication, authorization, charging functions, roaming, and privacy functions. For determining position, SUPL generally implements A-GPS, A-GNSS, or similar technology to communicate location data to a designated network node over Internet Protocol (“IP”).
FIG. 2A illustrates an exemplary architectural diagram for SUPL. The illustrated entities represent a group of functions, and not necessarily separate physical devices. In the SUPL architecture, an SLP 201 and SET 207 are provided. The SLP 201 generally includes a SUPL Location Center (“SLC”) 203 and a SUPL Positioning Center (“SPC”) 205. The SLC and SPC optionally communicate over the LIp interface, for instance, when the SLC and SPC are deployed as separate entities. The SET 207 generally includes a mobile location services (“MLS”) application 209, an application which requests and consumes location information, or a SUPL Agent, a service access point which accesses the network resources to obtain location information.
For any SET, an SLP 201 may perform the role of the home SLP (“H-SLP”), visited SLP (“V-SLP”) or emergency SLP (“E-SLP”). An H-SLP for a SET includes the subscription, authentication, and privacy related data for the SET and is generally associated with a part of the SET's home PLMN. A V-SLP for a SET is an SLP selected by an H-SLP or E-SLP to assist in positioning thereof. An E-SLP for a SET is an SLP associated with or contained in the PLMN serving the SET. The E-SLP may perform positioning in association with emergency services initiated by the SET.
The SLC 203 coordinates operations of SUPL in the network and interacts with the SET over the User Plane bearer to perform various functions including, but not limited to, privacy, initiation, security, roaming, charging, service management, and positioning calculation. The SPC 205 supports various functions including, but not limited to, security, assistance delivery, reference retrieval, and positioning calculation.
SUPL session initiation is network-initiated or SET-initiated. The SUPL architecture provides various alternatives for initiating and facilitating SUPL functions. For example, a SUPL Initiation Function (“SIF”) is optionally initiated using a Wireless Application Protocol Push Proxy Gateway (“WAP PPG”) 211, a Short Message Service Center (“SMSC/MC”) 213, or a User Datagram Protocol/Internet Protocol (“UDP/IP”) 215 core, which forms user plane bearer 220.
The operation of UPL is shown in FIG. 2B. Secure User Plane Location is a standard specification for UPL. Location requests come to the SLP 201 from external applications or from the end-user device itself. If a data session does not exist between the SLP 201 and the device 207 already, then the SLP 201 may initiate a request such that an IP session (user plane bearer 220) is established between the device 207 and the SLP 201. From then on, the SLP 201 may request measurement information from the device 207. The device may also take measurements from the network 107 or from external systems such as GPS 210. Because there is no control plane connectivity to the network, the SLP 201 cannot directly request any measurement information from the network 107 itself. More information on SUPL, including the Secure User Plane Location Architecture documentation (“OMA-AD-SUPL”), may be readily obtained through OMA.
The SUPL Location Platform is a location server defined as part of the SUPL specification standardized by the OMA. It uses the User plane Location Protocol to determine the position of a SET. Each SET has a Home SLP (H-SLP) with which it has a special trust relationship
The Http Enabled Location Delivery (HELD) protocol is a Layer 7 location configuration protocol used for retrieving location information from a Location information server (LIS) within an access network. The protocol includes options for retrieving location information in two forms; by value and by reference. The device may acquire a literal location object describing the location of the device. If the mobile device requests a location by value it may request that the LIS create a PIDF-LO document. The device may request that the LIS provide a location reference in the faun of a location Uniform Resource Identifier (URI_or set of location URIs allowing the device to distributes its location information by reference. Both of these methods may be provided concurrently from the same LIS. The protocol is an extensible application-layer protocol. The HELD protocol is defined independently of any lower layers used to transport messages from one host to another. Generally HELD relies upon the underlying transport layer to provide authentication, confidentiality and protection.
FIG. 3 is an illustration of a mobile device interaction with the local access network utilizing its HELD Client. The LIS, is a network server that provides devices with information about their location. Devices that require location information are able to request their location from the LIS. In the architectures developed by the Internet Engineering Task Force (IETF), National Emergency Number Association (NENA) and other standards forums, the LIS is made available in the IP access network that connects the device to the Internet. In other modes of operation, the LIS also provides location information to other requesters relating to a target device. The HELD protocol relies upon the location information server to provide location information to the recipient 303.
A LIS 309 is responsible for providing that location information to devices within an access network 307. The LIS uses knowledge of the access network and its physical topology to generate and serve location information to devices. Each access network retains specific knowledge about topology and information regarding the appropriate LIS that has the specific knowledge necessary to locate a device. Automatic discover of the LIS is important where there is any chance of movement outside a single access network. Reliance on static configuration may lead to unexpected errors if a device moves between access networks.
Dynamic Host Configuration Protocol (DHCP) is a computer networking protocol used by hosts to retrieve IP address assignments and other configuration information. DHCP allows the access network provider to specify the address of a LIS as part of network configuration. If the device is able to acquire a LIS URI using DHCP or other protocol than this URI may be used directly. (A Uniform Resource Identifier (URI) is a compact sequence of characters that identifies an abstract or physical resource. A location URI identifies a geographic location using a textual representation of the location's spatial coordinates in either two or three dimensions.)
An access provider (AP) operates the LIS so that devices (and targets) may retrieve their location information. The LIS exists since not all Devices are capable of determining location information, and in many cases it is more efficient to determine the location information with assistance from the LIS.
Typically, the device discovers the URI for the LIS for sending the HELD protocol requests from it initialization over the access network. The product of the LIS discovery process is one or more Http URI. These URIs may be used for location configuration using HELD. Additional information regarding automatic discovery may be found in Thomson, Winterbottom, “Discovering the local Location Information Server (LIS)” IETF, Feb. 9, 2009, the entirety of which is incorporated by reference.
The access network 307 is the network that provides a connection between a device and the Internet. The access network 307 may include the physical infrastructure: cabling, radio transmitters, switching and routing nodes and servers. The access network covers the infrastructure necessary to provide a physical connection to the Internet. The access network also covers the services required to enable IP communication, which include servers that provide addressing and configuration information such as DHCP and Domain Name Server (DNS) servers. DHCP is a computer networking protocol used by hosts to retrieve IP address assignments and other configuration information.
In certain situations such as roaming, the SLP may not have enough information about network topology to determine an accurate location estimate and may need assistance from another SLP. Additionally, the LIS may not be able to provide a literal location or a literal location with the accuracy required by the request. The present subject matter is directed to leveraging the information inherently provided by the LIS to the HELD client to assist the H-SLP in determining an appropriate V- SLP for determining a location estimate.
The prior art does not explicitly define how H-SLP servers determines the V-SLP. Thus, there is a need in the art to overcome, the limitations of the prior art and provide a novel system and method for SUPL roaming in networks.
The current subject matter leverages the discovery process of the HELD client to assist the H-SLP in selecting an appropriate V-SLP in order to locate the device.
In order to obviate the deficiencies of the prior art, the present subject matter discloses a novel method for assisting in the selection of a visiting secure user plane location platform (SLP) for a mobile device. The method includes accessing a network and searching a location information server associated with the access network using a HTTP protocol. The method includes receiving identifying information from the LIS; and, transmitting the identifying information along with the characteristics of the wireless communications network to the H-SLP. The H-SLP using the LIS to aid in the selection of a V-SLP to locate the mobile device.
It is further an object to present a novel method of selecting a second secure user plane location platform (SLP) for a mobile device, the mobile device having an integrated secure user plane location (SUPL) and HTTP enabled location delivery (HELD) client. The method including initiating a SUPL session; accessing a network and requesting identity information is received at the mobile device and is transmitted along with network measurements to a first secure user plane location platform. The first secure user plane location platform selecting the second SLP based upon the identity of the LIS and whether the LIS is associated with a SLP.
It is still an object of the disclosed subject matter to present a method of locating a SUPL enabled terminal (SET) mobile device having a HTTP enable Location delivery (HELD) client. The method includes initiating a location session; requesting network measurements of a wireless communications network form the mobile device. Information regarding LISs associated with a network assessed by the mobile devices as a HELD client along with the requested network measurements is received and V-SLP is selected based upon the identifying information
It is still another object to present a system for selecting a V-SLP for a roaming mobile device. The system includes the mobile device which includes a SUPL enable Terminal (SET) having an integral HELD client; a local Access network assessable by the HELD client of the SET; the local access networking having a LIS associated with a SLP. The system further includes a H-SLP associated with the mobile device. The local access network provides identity information of the LIS to the mobile via the HELD client which in turn provides the identity information to the H-SLP, the H-SLP determines a V-SLP based on the identity information.
Another embodiment of the present subject matter provides a method for providing assistance data to a mobile device in a wireless communications network. These embodiments and many other objects and advantages thereof will be readily apparent to one skilled in the art to which the disclosed subject matter pertains from a perusal of the claims, the appended drawings, and the following detailed description of the embodiments.